Theory of differential semblance velocity analysis by wave-equation migration
نویسندگان
چکیده
Prestack wave equation migration using the double square root equation produces prestack image volumes free of artifacts, even in the presence of multipathing due to complex structure. In particular image gathers in angle or offset ray parameter are flat at correct velocity, and gathers in offset are concentrated at zero offset. Differential semblance measures the deviation from flatness or concentration, and provides a method of automatic velocity updating via optimization. The adjoint state method gives a convenient computation of the differential semblance gradient as an addendum to prestack depth extrapolation.
منابع مشابه
Differential Semblance Velocity Analysis by Reverse Time Migration: Image Gathers and Theory
Velocity models can be automatically updated by differential semblance velocity analysis (DSVA). To overcome the dip limitations associated with the one-way wave equation based imaging algorithms, we propose in this study that the common image gathers can be defined other than in horizontal offset domain within the reverse time migration(RTM) framework, where two-way wave equation is solved as ...
متن کاملDSR Migration Velocity Analysis by Differential Semblance Optimization
The relative efficiency of Common Azimuth wave equation depth migration based on the double square root equation makes it an attractive engine for use in automated velocity updating schemes. One such automated velocity analysis procedure is Differential Semblance Optimization, which constructs velocity updates to reduce, and eventually minmize, a quantitative measure of image gather misfocussin...
متن کاملWave-equation extended images for semblance and depth focusing velocity analysis
Conventional velocity analysis applied to images produced by wave-equation migration makes use either of moveout information from space-lags, or of focusing information from timelags. However, more robust velocity estimation methods can be designed to take advantage at the same time of the moveout and focusing information provided by the migrated images. Such joint velocity estimation requires ...
متن کاملAnalysis of converted-wave extended images for migration velocity analysis
Converted-wave data have been recognized to have potential in complementing conventional compressional data. However, imaging for converted-waves is more difficult mainly due to the need for estimating shear-wave velocities, in addition to compressional-wave velocities. The common practice is to obtain the shear-wave velocity by registering PS and PP images. Despite its low cost, this procedure...
متن کاملAutomatic Velocity Analysis via Shot Profile Migration
Shot profile migration provides a convenient framework for implementation of a differential semblance algorithm for estimation of complex, strongly refracting velocity fields. The objective function minimized in this algorithm may measure either focussing of the image in offset or flatness of the image in (scattering) angle. Velocity estimation based on this measure of data-model consistency us...
متن کامل